A cleanout fitting is a pipe fitting normally provided in a conduit and having a laterally openable well that is closed by means of a removable cover. When the cover is opened a snake or other tool can be introduced into the conduit to clean same.
It is known to provide such a fitting at the well with one or more inserts, which can be constituted as filters, flow restrictors or, most commonly, check valves. Removing the cover of such a fitting allows the insert to be serviced. In the case of a check valve such a servicing is normally constituted by cleaning of the pivots for the valve flap and clearing of the seat.
Such a check-valve insert typically has a seat-forming flange that is secured within the cleanout fitting at the well, and which in turn carries a pivot for a valve body. The flange is secured to an inwardly directed ridge formed in the cleanout fitting and itself formed with threaded holes into which engage screws passing through corresponding holes in the flange of the check valve.
The mounting, removing, and general servicing of such a check valve is an onerous task. What is more after some use it is frequently very difficult to mount a replacement or a cleaned check valve in the fitting while forming a good seal. It is also normally impossible to retrofit such a cleanout fitting with a check valve, as after some use it becomes impossible to fit an insert of this type into the cleanout fitting on the worn and normally fouled mounting surface.
A problem with those units having an external actuator for holding the check valve closed is that the valve body, after being held for some time against the respective valve seat, freezes to this seat, so that even if the force holding it there against is relieved the valve does not open. In such an arrangement it is normally necessary to open the cleanout fitting to free the frozen valve body, an operation which in fact renders the provision of an external actuator for the valve body largely superfluous.